sea-floor spreading

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vocabulary

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mid-ocean ridge :the longest chain of mountains in the world
sonar :the wave that scientists send down to see how long the mid-ocean ridge is
sea-floor spreading :the process the continually adds new material to the ocean floor
deep-ocean trench :an under water canyon
subduction :is the process which the ocean floor sinks beneath a deep-ocean trench and back into the mantle

outline

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mapping the mid-ocean ridge

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• use sonar
  • longest chain of mountains in the world

evidence from sea-floor spreading

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• evidence from molten material,magnetic strips and drilling samples

subduction at deep-open trenches

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• the new oceanic crust is very hot

think of sea-floor spreading as a giant conveyor belt

subduction and Earth's ocean

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• the ocean floor is renewed about every 200 million years
  • the pacific ocean is shrinking
    • the Atlantic ocean is growing

bibliography

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picture of sea floor spreading got from
http://images.google.com/imgres?imgurl=http://www.unil.ch/webdav/site/igp/shared/stampfli_teaching/T25-40.jpg&imgrefurl=http://www.u
nil.ch/igp/page22605_fr.html&h=342&w=553&sz=27&hl=en&start=8&tbnid=SNxGSOasgvlpwM:&tbnh=82&tbnw=133&prev=/images%3Fq%3DSea-Floo
r%2BSpreading%26gbv%3D2%26svnum%3D10%26hl%3Den%26sa%3DG

youtube video link

http://www.youtube.com/watch?v=5JzUgi6YNlY&eurl=http%3A%2F%2Fteamforce%2Ewikispaces%2Ecom%2FKGMK%2B1%2E4